Bolster spring unit



Patented Apr. 25, 1939 PATENT OFFICE BOLSTER SPRING UNIT Donald F. Sproul, Chicago, Ill., assignor to Cardwell-Westinghouse Company, a corporation of Delaware Application October 16, 1936, Serial No. 105,859

9 Claims.

This invention relates to spring devices, and, more particularly, to spring units for supporting railway car bolsters and the like.

One of the objects of the invention is the provision of a new and improved spring unit of the friction type having a novel arrangement of friction elements therein.

Another object of the invention is the provision of a new and improved spring unit having a novel spring and friction mechanism arrangement whereby greater frictional resistance is offered to the expansion of the unit than to its compression.

A further object of the invention is the provision of a new and improved spring unit provided with a single cap member and having novel means for holding the parts in assembled relation.

Another object of the invention is the provision of a new and improved bolster spring unit that is inexpensive to manufacture, composed of few moving parts, easily assembled, that is eflicient in use, and that is not likely to become broken or get out of order.

Other and further objects and advantages of the invention will appear from the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a side elevation of a railway truck with parts broken away showing the invention in position therein;

Fig. 2 is a vertical section of a spring unit;

Fig. 3 is a section on the line 33 of Fig. 2;

Fig. 4 is a perspective view of one of the fric-' tion shoes; and

Fig. 5 is a perspective view of the wedging member.

Referring now to the drawing, the reference character 5 designates a railway truck having the side frame 6 which is provided with the conventional opening I in which the spring assembly 8 for supporting the bolster, is mounted. This assembly comprises the helical springs 9, and one or more of the improved spring units I0. Since the details of the truck constitute no part of the i3 present invention, it is not thought necessary to further illustrate or describe the same.

The device is adapted to be used for supporting bolsters on railway trucks and is of such a size that it may be substituted for one or more of the conventional springs now in use for supporting the bolster. In the use of free-acting springs, such as the conventional helical springs, for supporting the bolster of railway cars, harmonic action often develops which may lead to serious consequences. This harmonic action is caused by synchronizing the speed with the movement of the car over uneven tracks or of the vertical movement of the car due to fiat wheels.

The present invention is adapted to be used in connection with free acting springs for dampening the vibration of the springs, and, at the same time, increase the capacity of the spring assembly. This increase in capacity is due to the frictional resistance to the compression of the unit. In order that the unit may properly dampen the vibration of the spring assembly, it is desirable that friction be introduced to prevent the free movement of the spring during its expansion.

In the present invention, the parts are so constructed that there is a greater frictional resistance to the expansion of the spring than to the compression thereof.

In the form of construction selected to illustrate one embodiment of the invention, which is by way of example only, the unit I0 is provided with a follower or cap plate II at its upper end. This plate may, and preferably does, have a depressed portion l2 provided with an axial opening I 3 through which a bolt I4 extends. The head of the bolt is adapted to seat in the recess I5 formed by the depressed portion. An outer or main helical spring I6 encircles the depressed portion I2 and seats against the under side of the cap plate II. The lower end of the spring is so constructed that it may rest flat on its support, such as a spring plank or the like.

The spring may be circular or rectangular in cross section, as desired. As shown, it is circular and mounted within the same are a plurality of friction shoes I! which are adapted to frictionally engage the inner surface of the intermediate coils of the spring. Any suitable number of shoes may be employed. As shown, two are used. Each of these shoes is provided on its lower surface with an upwardly and inwardly extending wedge or friction face or surface I8 and with a ledge or shoulder I9 above the wedging surface I8. The outer surface of the shoes is shaped to conform to the inner surface of the main spring I6 and is also preferably tapered on the side edges toward the ends, as shown at 20. Their inner surfaces together form a cylindrical cavity with in which an inner or auxiliary spring 2I is mounted. Each of the ledges I9 has a semicircular recess 25 which together, when the parts are assembled, form an opening through which the bolt I4 extends. The upper end of the auxiliary spring surrounds a boss 22 on the lower surface of the depressed portion I2 of the cap II.

A wedging member 23 engages the wedging faces I8 of the shoes and is provided with an axial opening 30 through which the bolt l4 extends. The lower end of the bolt is threaded and provided with an adjusting nut 24 by means of which the tension of the spring 2| may be adjusted. In assembling the device, the nut 24 is adjusted so as to place considerable initial compression on the auxiliary spring 2| whereby the shoes will be forced outwardly into frictional engagement with the inner surface or turns of the main spring IS.

The spring 2| is of such strength that when it is compressed, even though there be a great amount of friction between the shoes and the main spring I'B, the spring I 6 and shoes will move substantially as a unit.

In the operation of the device, it will be seen that as the spring unit is compressed and the shoes move downward in frictional contact with the spring, there will be a drag on the shoes, which in turn will lessen to a more or less extent, the wedging action of the wedge thereby lessening to a certain extent, the friction between the shoes and spring l6. On the other hand, when the gear is released, the frictional resistance or drag between the shoes and the main spring I 6 will tend to retard the movement of the shoes whereby the wedge 23 will tend to force the shoes outwardly still further and create a greater frictional resistance to the expansion of the unit than to its compression.

In assembling the device, the spring 2| is placed under initial compression and remains under compression during the operation of the unit.

- When the parts are assembled, the device is a unitary structure with a cap on one end only, thereby eliminating one cap member usually employed in devices of this character. The compression on the spring 2| may be adjusted by means of the nut 24,, to increase or decrease the frictional resistance to the compression and expansion of the unit, as may be desired.

It is thought from the foregoing taken in connection with the accompanying drawing that the construction and operation of my device will be apparent to those skilled in the art and that changes in size, shape, proportion and details of construction may be made without departing from the spirit and scope of the appendedclaims.

I claim as my invention:

1. In a spring unit, an outer spring, friction shoes frictionally engaging said spring, said shoes having wedging surfaces, a wedge member engaging said surfaces, a cap engaging the upper end of said spring, and a second spring engaging said shoes and cap for causing said shoes to frictionally engage said outer spring when said unit is compressed.

2. In a spring unit, an outer helical spring, a pair of shoes frictionally engaging the interior of said spring, downwardly facing wedging faces on said shoes, shoulders above said faces, a wedge element engaging said faces, an inner spring engaging said shoulders, and a tension member between said inner spring and wedge element for holding said inner spring under tension for forcing said shoes outward into frictional contact with said outer spring.

3. In a spring unit, an outer spring, an inner spring, friction shoes engaging said outer spring, and means cooperating with said inner spring and shoes for causing a greater frictional resistance to the expansion of said unit than to its compression.

4. A spring unit comprising a main spring, a cap for one end of said spring, a plurality of shoes within said spring, a wedging member for forcing said shoes into frictional contact with said spring, an auxiliary spring compressed between said cap and shoes, and means engaging said cap and wedging member for adjustably initially compressing said auxiliary spring.

5. A spring unit comprising a main spring, a plurality of shoes frictionally engaging said spring, a wedge member engaging said shoes, an auxiliary spring for engaging said shoes, and means for adjustably compressing said spring for causing said member to force said shoes into frictional contact with said main spring.

6. A spring unit comprising a main spring, a plurality of friction shoes, and means for forcing said shoes into frictional contact with said spring with a less force on the compression of said unit than on its release.

7. A spring unit comprising a main spring, a spring cap on one end of said spring, a plurality of friction shoes which together form a spring cavity, a spring in said cavity and engaging said cap and shoes, a wedge member below said cavity engaging said shoes for forcing the same outwardly into contact with said main spring, and a bolt extending through said cap, inner spring and wedge member for holding said inner spring under initial compression.

8. In a spring unit, a load supporting spring, friction shoes associated with said spring; a Wedge member for forcing said shoes into frictional engagement with portions of said spring, and means for causing a greater wedging action of said member during the expansion movement of said unit than during its compression whereby there is greater frictional resistance to the expansion of said unit than to its compression.

9. In a spring assembly for resiliently supporting a vehicle body, a load supporting spring, means including friction and wedging mechanism associated with said spring for resisting the free movement of said spring during either its compression or its expansion, said means including friction members, wedging means and spring means for holding the said members and wedging means in frictional engagement with the wedging surfaces of said wedging means, all wedging surfaces of said wedging means converging toward said spring means so that compression of the load supporting spring tends to relieve the wedging means, whereby there is produced a greater frictional resistance to the expansion of the spring than to its compression, during use.

DONALD F. SPROUL. 

